Ten minutes of ischemia is superior to shorter intervals for the remote ischemic conditioning of human microcirculation.

Abstract

Surgical flaps have become reliable tools in the microsurgical armamentarium, but are still faced with tissue loss due to impaired perfusion which can lead to complete flap failure. Remote Ischemic Conditioning (RIC) has been demonstrated to be an effective way to improve microcirculation in surgical flaps in humans. However, little is known about the optimal amount and length of RIC cycles. Determination of a superior protocol for RIC of cutaneous microcirculation in humans. 60 healthy volunteers were randomized into different groups and received a RIC protocol, consisting of three cycles of either 1 second, 1, 5, or 10 minutes of ischemia followed by ten minutes of reperfusion. RIC was applied with a inflatable tourniquet placed on the upper arm. Changes in microcirculation were assessed via combined laser doppler/spectroscopy (O2C device) at the anterior lateral thigh. Relative increase at the end of conditioning vs. baseline measurements was calculated and compared between groups. RIC caused significant changes in cutaneous microcirculation (p < 0.05) which were more pronounced in groups with longer ischemia intervals. The ten minutes group was significantly superior. A conditioning protocol containing three cycles of ten minutes of ischemia is superior to protocols with shorter ischemia intervals for RIC of cutaneous microcirculation.